FIELD OF INVENTION
The present invention relates to a self-steam aging box and method thereof for the aging Steel-making LD slag by means of artificially swelling the slag in a short time by using steam so as to obtain a product applicable for use in different forms,

BACKGROUND ART
Traditional methods:
The slag is generally cooled in an open area which causes not only an aesthetic challenge but also needs several hours for the core of the slag to solidify and cool sufficiently. lt faces a number of safety and operational challenges. Typically Slag contains free lime, entrapped metallic Fe, FeO, MgO, High FeO is not good for cement. It absorbs moisture and CO2 from atmosphere leading to volume expansion/cracks and is not suitable for construction use. This huge quantity of unused slag is lying dumped on the precious land of steel plant.
After cooling, BOF Slag is transferred to slag yard for crushing and metal separation is done. Separated metallic part is recycled in BOF. Transportation of air & water cooled slag from slag yard to crushers and metal separators (magnetic separation) needs additional safety & operational risks.
BOF Slag is collected in slag pots and Slag pot is handled by slag carrier. Molten slag is introduced through launder by tilting the slagpot with the help of carrier which overcomes the environmental problems of furnace slag.
Disadvantage of traditional methods:-
Air cooling and dry handling of slag poses various challenges. Firstly, the dumping of liquid slag in an open area causes not only an aesthetic challenge but also makes fume capture impossible.
Secondly, handling air cooled slag faces a number of safety and operational challenges.
Water spray is also used to accelerate the cooling rate. However, potential for molten material/water explosions remain ever present and the delay of slag cooling may cause delay of slag yard availability for furnace operations.
Removing semi-molten slag from a pit poses danger to both personnel and equipment, even when using modified mobile equipment or "hot' machines.
Waste from BOF Slag is either dumped or thrown out in open space, creating problem of space for the dumping of such huge wastes and a big concern for environment.

OBJECT OF INVENTION
The principle object of the present invention is to provide an environmental control in slag aging process.
Another object of the ore sent invention is to provide slag conditioning and energy recovery for aging.
Another object of the present invention is to reduce investment and operating cost.
Another object of the present invention is to reduce the steam requirement and dust emission inside building and further reduce the space requirement.
Yet another object of the present invention is to optimize water consumption compared to other methods and reduce the cooling time.

SUMMARY OF INVENTION
Basic process of self-steam aging technology is:
Make the hydration reaction with Free CaO and MgO to reduce the expansion limit < 0.5% for using LD Slag in construction of road and building materials.
Refinement of the technology ensures that slag cools in the quickest and most efficient way possible.
Aging Box bottom is to be cover with 20 to 40 mm LD slag uniformly distributed up to height of l feet.
Keep the Front door closed.
Open the steam valve moderately from common steam line available at side to purge the Steam from bottom of aging Box till it complete, 12 Heats.
Slag is tipped into aging Box in a controlled manner.
Put the top cover on the self steam aging Box.
Connect water pump line and tie safety chain on the top cover of aging box.
Start self generated steam pump first then start high pressure water pump to pour water from the top.
Slag is to be cooled from the Top for 2 Hours with a high pressure water (1•2 bar) and self generated steam from bottom.
Once the core of slag is solidified & cooled sufficiently, then stop all the water spray & steam injecting.
Remove the Safety chain & water connection of top cover.
Remove the top cover and front door of self steam aging box.
Remove the sufficiently cooled slag from aging box with excavator.
Total time taken for this process is only 9 Hours : (1Hour for bed preparation +5 Hours for collection of slag of 12 Heats + 2 Hours for Cooling+1 Hour for removing slag from aging box).
Therefore such as herein described there is provided a self-steam aging box for aging of the steel-making slag containing calcium oxide and magnesium oxide comprising of a front and top open sealable steel box preferably configured for charging slag into the said box with temperature and pressure resistant including a plurality of inlet / outlet for pressurized steam injection from bottom and water inlet from top and water outlet from bottom; an external steam supplying pressure pump configured for supplying pressurized steam into said box in order to heat said slag and to raise the temperature and pressure in said pressure vessel and to hydrate the calcium oxide and magnesium oxide to calcium hydroxide and magnesium hydroxide respectively while discharging condensed hot water to prevent lowering the temperature of the surface of the slag grains wherein the said box is configured for keeping the interior in a condition of Saturated Steam at a prescribed pressure and temperature for a predefined time and thereafter discharging the Steam from said pressure vessel to reduce the pressure to atmospheric pressure; wherein the water is supplied from the top inlet in order to maintain temperature and cooling; and wherein the metal and slag is loosened by expansion reactions, and free lime and free metal material can be easily separated by magnetic separator / rumbler from said box.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1 (a) illustrates the self-steam aging box with steam injector and water inlet / outlet in accordance with the present invention;
Fig. 1 (b) illustrates the front door cover of the said self-steam aging box with steam injector and water inlet / outlet in accordance with the present invention;
Fig. 1 (c) illustrates the top cover of the said self-steam aging box with steam injector and water inlet / outlet in accordance with the present invention;
Fig. 1 (d) illustrates the self steam aging box (open – view) in accordance with the present invention;
Fig. 1 (e) illustrates the bottom steam pipe in accordance with the present invention;
Fig. 1 (f) illustrates the slag bucket in accordance with the present invention;
Fig. 1 (g) illustrates the steam pipe guard in accordance with the present invention;
Fig. 2 illustrates the testing pot in accordance with the present invention;

DETAILED DESCRIPTION
Flux, added to refine steel, forms a component of the steelmaking slag. It is of particular significance that CaO and MgO contained in the flux remain partly inactive and reside in the slag or crystallize while the slag Is solidified and cooled. These inactive materials, referred to as free-CaO and free-MgO, react with water and in the process their volume nearly doubles through hydration. As a measure to prevent that, the steelmaking slag is subjected to the aging treatment process, whereby the following hydration reaction is completed by the time the slag is shipped:
CaO + H2 O Ca(OH)2, MgO + H2 O Mg (OH)2 .
There are two representative methods of aging treatment: normal aging treatment, whereby the hydration reaction is allowed to take place by natural rainfall in the yard, and accelerated aging treatment, whereby the hydration reaction is induced to complete it in a shorter period of time. The accelerated aging treatment processes that may be put into practical use include "water steam aging treatments" that uses high pressure water and steam.

Fig. 1 (a) - (g) shows an overall structural view of the first embodiment of the present invention, i.e. the embodiment 1.
In the apparatus, a crusher for crushing steel-making slag and a conveyor for transferring the crushed slag to a charging slag bucket are arranged. A self-steam aging box is disposed below at the discharging opening of said charging slag bucket to charge the slag transferred via the conveyor and the charging slag bucket. Said self-steam aging box has closable lids of a dome type top lid and a front door so as to keep steam in the interior of said vessel at a predetermined pressure/temperature. The upper portion of the self-steam aging box is connected, via a pipe having a valve, to a steam generator for supplying steam into the self-steam aging box. To the lower portion of the self-steam aging box, a pipe equipped with a steam trap is connected so that hot water is discharged there from. A pipe having a valve is connected to the upper portion of said self-steam aging box, to reduce the internal pressure of the self-steam aging box after aging. Further, a slag container may be disposed below the lower portion of the self-steam aging box so as to discharge aged slag out of the self-steam aging box after aging is completed. By opening the bottom lid the steel-making slag is supplied into the slag container.
An aging vide experimental testing pot with this apparatus is described according to Fig. 2 showing temperature and pressure changes during the process.
(1) Charging
The top lid of the self-steam aging box is opened, steel-making slag is charged from slag bucket into the self-steam aging box, and the top lid is closed to seal the self-steam aging box. (Required time ti) Temperature and pressure in the self-steam aging box do not change at this step.
(2) Heating and pressurizing
By opening the valve the steam is supplied from the steam generator to the self-steam aging box. The steam is condensed into hot water by contact with the internal wall of the self-steam aging box and the steel-making slag and thereby transferring its latent heat to the self-steam aging box and the steel-making slag. Thereby the average temperature of the steel-making slag and the self-steam aging box is raised. Metal and slag is loosened by expansion reactions, thus free lime and free metal material can be easily separated by magnetic separator/rumbler and metal free slag can be used in construction and Road making. The said raising of the average temperature allows the elevation of the internal pressure of the steam. The generating rate of the hot water is large until the self-steam aging box and the steel-making slag are heated enough. Hot water accumulated in the vessel soaks slag in the lower portion of the vessel interrupting heat transfer of latent heat from the steam to the steel-making slag. Consequently, the temperature of steel-making slag is decreased. This hot water is discharged from the lower portion of the self-steam aging box via the pipe equipped. The amount of discharged hot water corresponds to the amounts of generating rate of hot water. (Required time tp)
(3) Temperature holding
Since the pressure of the steam supplied from the generator is kept constant, the increase of the pressure in the vessel decreases the amount of the steam supplied from the generator, thus decreasing the generating rate of hot water generation. The pressure in the vessel soon becomes nearly equal to the pressure of the steam supplied from the steam generator. In this condition, steam is supplied and the hot water is discharged continuously to keep the temperature and the pressure at a predetermined value for time to promote hydration. As the hydration CaO+H2 O?Ca(OH)2 proceeds, the steam flow rate decreases. (Required time ts)
(4) Pressure reducing
Upon completion of the aging process, the valve is closed and the valve is opened. The steam in the self-steam aging box is thus released to the atmosphere from the upper portion of the self-steam aging box via the pipe to reduce the pressure in the self-steam aging box to atmospheric pressure. The average temperature is lowered. (Required time td)
(5) Discharging process (Required time to)
Finally, by opening the bottom lid of the self-steam aging box, the slag in the self-steam aging box is discharged in the slag container, so that the average temperature of the slag and the vessel decreases as well as the condensing temperature of steam. The particles of slag come in contact with steam and water bubbling of slag occurs, which effect aging faster. Water poured from the top of aging box is converted into steam due to the thermal energy of slag and this steam is recirculated to the bottom to produce bubbling effect inside the slag particles and makes slag cool faster. As a result oxidation of slag and metal leads to expansion which segregates slag and metal faster.
Aging is completed according to the above steps. Thereafter, both the lid of the self-steam aging box and the valve are closed so that the above-mentioned processes (1) to (5) are repeated and the next aging of slag is started.
The duration required for aging of slag is 9 hrs.
It is desirable that the material slag should be crushed depending on the standards of aggregate for road materials. Since the grains collapse during aging, the size of the grain may be made slightly larger. If the grain diameter of the slag is too large, as the unslaked lime at the grain surface layer becomes slaked lime, the hydration reaction of the unslaked lime in the grains hardly proceeds, and the aging time may be extended.
High tensile strength with highly oxidized of free lime (CaO), MgO, Fe and aged slag material with expansion strength less than 0.5%,materials are free from metal particles is readily available for cement processing and road making material.
Present invention relates to providing slag free of CaO and MgO and metal particle and dust.
Particles of slag come in contact with steam and water bubbling of slag occurs, which effect aging faster. Water poured from the top of aging box is converted into steam due to the thermal energy of slag and this steam is recirculated to the bottom to produce bubbling effect inside the slag particles and makes slag cool faster. As a result oxidation of slag and metal leads to expansion which segregates slag and metal faster.
The slag produced in the conventional process is lying dormant for several years and occupying precious land of Steel Plant. The new invention will make the aging process faster (within 9 hours) to produce slag material, which is free from metal particles and can be used for construction purposes (cement processing and road making).
Comparison of performance between atmospheric open air aging and self-steam aging (64,000 ton/month).

Salient feature of the innovation:
Reduction in dust emissions (improved environmental performance).
Reduction in slag size (potential need for less crushing / easier processing).
Reduction in slag expansion (potential need for direct using after magnetic separation and less stock piling area).
Reduced foot print requirement (Reduction in land requirement for processing).
Metal and slag is loosened by expansion reactions, thus free lime and free metal material can be easily separated by magnetic separator/rumbler and metal free slag can be used in construction and Road making.
Clean shop floor environment due to less dust emissions and Optimum utilization of water and steam.
In Atmosphere aging process, we can use only 19% of Total Slag generated.
In Self Steam aging, we can use up to 40 to 50% of Total Slag generated.
In build safety features are present in the design:
a) Top Cover is dome shaped to withstand excess pressure in the Self Steam aging Box.
b) High pressure Steam Extractor is being used to release steam pressure from aging Box.
c) Cooling is done sequentially from Top to bottom.
d) Cooling pipes bottom has been covered with Safety Plates and 20-40 LD Slag to facilitate free flow of steam and prevent damaging of pipes.
e) Top Cover is cooled with a Top water cooling system.
f) Safety chain of the TOP Cover is to be used as a safety precaution in case of any unwanted explosions.
g) Dust Filter is connected with the steam line to remove dust particles from self-generated steam.
h) Accumulated filter dust is cleaned automatically when filter strainer is jam.
i) Special Slag bucket are designed to pour the slag uniformly inside Aging Box.
Advantage of self steam aging box technology are:
Two different processes are combined for LD Slag aging.
Steam purging from bottom will help to remove Free CaO and MgO from LD Slag & accelerate cooling from bottom.
Water is poured from the Top to cool, thus causing hydration reaction with free CaO and MgO.
Steam and water both are used in this self steam aging process, thus making the Hydration reaction faster and uniformly slag core solidifies & cools sufficiently.
Uses of slag after self steam aging are:•
Road making, Cement making, Construction work like Raw materials to manufacture Concrete brick, Railway ballast, Paver block and vitrified ceramic tile.
Inventive step
Self-steam aging of BOF slag, comprising purging steam from bottom & pouring water from top which will help to remove free CaO and MgO in a faster way through bubbling of each slag particle that comes in contact with water and steam, thus effect aging faster.
-having use of self generated steam in the process, so that utilization of external energy is less.
-having metal and slag bonding become loose because of fast expansion reaction. In this process free lime and free metal oxidizes faster and metal can be recovered 95% from slag by rumbler, which can be reused in steelmaking and reduced cost of production.
-having removed the metallic part from slag and oxidized the free particle of CaO and MgO, Slag can be used for road and building construction material in bigger way.
-having good bubbling process of slag with steam and water will reduce time required for aging process significantly (<1/2 Time) of any other conventional process of aging. Instant uses of slag can be done.
-having slag handling cost is reduced due to self-aging slag size which is smaller than the conventional slag aging process.
-having less water consumption as compared with conventional slag aging
process.
-having use of self-generated steam which reduces process cost.
-having processing and material handling is highly safe as compared to conventional slag aging process.
-having less emission of dust as compared to conventional slag aging
process.
-having less space consumption as compared to conventional slag aging
process.

Although the foregoing description of the present invention has been shown and described with reference to particular embodiments and applications thereof, it has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the particular embodiments and applications disclosed. It will be apparent to those having ordinary skill in the art that a number of changes, modifications, variations, or alterations to the invention as described herein may be made, none of which depart from the spirit or scope of the present invention. The particular embodiments and applications were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such changes, modifications, variations, and alterations should therefore be seen as being within the scope of the present invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

WE CLAIM:

1. A self-steam aging box for aging of the steel-making slag containing calcium oxide and magnesium oxide comprising of:
a front and top open sealable steel box preferably configured for charging slag into the said box with temperature and pressure resistant including a plurality of of inlet / outlet for pressurized steam injection from bottom and water inlet from top and water outlet from bottom;
an external steam supplying pressure pump configured for supplying pressurized steam into said box in order to hit said steel-making slag and to raise the temperature and pressure in said pressure vessel and to hydrate the calcium oxide and magnesium oxide to calcium hydroxide and magnesium hydroxide respectively while discharging condensed hot water to prevent lowering the temperature of the surface of the slag grains;
wherein the said box is configured for keeping the interior in a condition of Saturated Steam at a prescribed pressure and temperature for a predefined time and thereafter discharging the Steam from said pressure vessel to reduce the pressure to atmospheric pressure;
wherein the water is supplied from the top inlet in order to maintain temperature and cooling and
wherein the metal and slag is loosened by expansion reactions, and free lime and free metal material can be easily separated by magnetic separator/rumbler from said box.

2. The self-steam aging box as claimed in claim 1, wherein said raising of the average temperature allows the elevation of the internal pressure of the steam.

3. The self-steam aging box as claimed in claim 1 to 2, wherein the Hot water accumulated in the vessel soaks slag in the lower portion of the vessel interrupting heat transfer of latent heat from the steam to the steel-making slag and thereby the temperature rising rate of steel-making slag is decreased.

4. The self-steam aging box as claimed in claim 1 to 3, wherein self-steam aging of BOF slag, comprising purging steam from bottom & pouring water from top which remove free CaO and MgO in a faster way through bubbling of each slag particle that come in contact with water and steam, effecting the aging faster.

5. The self-steam aging box as claimed in claim 1 to 4, wherein the said box is configured for the use of self generated steam in the process, so that utilization of external energy is less.

6. The self-steam aging box as claimed in claim 1 to 5, wherein the metal and slag bonding become loose because of fast expansion reaction and the free lime and free metal oxidizes faster and metal can be recovered 95% from slag by rumbler, which can be reused in steelmaking and reduced cost of production.

7. The self-steam aging box as claimed in claim 1 to 6, wherein said bubbling of slag with steam and water will reduce time required for aging process significantly (<1/2 Time) of any other conventional process of aging.

8. The self-steam aging box as claimed in claim 1 to 7, wherein the top Cover is dome shaped to withstand excess pressure in the Self Steam aging Box.

9. The self-steam aging box as claimed in claim 1 to 8, wherein the cooling is done sequentially from top to bottom and the cooling pipes at bottom is covered with Safety Plates and 20-40 LD Slag to facilitate free flow of steam and prevent damaging of pipes.
10. The self-steam aging box as claimed in claim 1 to 9, wherein a dust filter is connected with the steam line to remove dust particles from self-generated steam and the accumulated filter dust is cleaned automatically when filter strainer is jam.

11. A method for self-steam aging box for aging of the steel-making slag containing calcium oxide and magnesium oxide employing the self-steam aging box as claimed in any of the preceding claims.